When fluids are pumped through a conduit, such as a pipeline, friction resulting from the movement of the fluid over the inside surface of the conduit causes a pressure drop in the fluid which increases as the downstream distance from the pump increases. Because of the loss in pressure, it is usually necessary to install additional pumps at selected points along the pipeline to keep the fluid moving at the desired rate in the conduit. Sometimes it is desirable to increase the throughput of fluids through conduits but this cannot always be satisfactorily accomplished by installing additional booster pumps. The flow rate of the fluid through the conduit can also be increased by reducing the friction of the fluid in the conduit. Accordingly, it would be desirable to find an efficient technique for reducing the pressure loss due to friction, commonly referred to as "friction loss" or "drag".
One method of reducing friction loss in fluids moving through conduit is to inject into the fluid a substance which is capable of reducing the friction loss of the fluid moving through the conduit. Such substances must not only reduce the friction loss of the fluid, but must be compatible with the fluid and must not interfere with the intended use of the fluid.
A variety of polymeric materials have been used or disclosed for use as "fluid loss" additives. For example, U.S. Pat. No. 3,692,676 discloses the reduction of friction loss in hydrocarbon liquids flowing through pipelines by adding to such liquids small amounts of homopolymers or copolymers of alpha-olefins having from 6 to 20 carbon atoms. Fluid loss additives are also disclosed in U.S. Pat. No. 3,215,154, which teaches the use of polyisobutylene as a hydrocarbon liquid friction loss reducing agent; U.S. Pat. No. 3,434,485, which discloses the use of low molecular weight polybutene to reduce friction loss in a crude oil pipeline; U.S. Pat. Nos.: 3,351,079; 3,493,000; 3,559,664 and 3,682,187, which disclose the addition of copolymers of ethylene and propylene or other low molecular weight alphamonoolefin to hydrocarbon fluids as fluid flow friction loss reducing additives; and U.S. Pat. No. 3,454,379, which describes the addition of low molecular weight polyethylene to distillate hydrocarbon fuel oil to improve the pumpability of the fuel oil.
Friction loss additives vary in their effectiveness. Usually the more effective additives are those of higher molecular weight. More often increasing the molecular weight (inherent viscosity) of the polymer increases the percent drag reduction obtained, within the limitations that the polymer must be capable of dissolving in the hydrocarbon liquid in which friction loss is effected.
According to this invention compositions comprising hydrocarbon liquids having reduced friction loss are obtained by adding to such hydrocarbons small amounts of high molecular weight non-crystalline, hydrocarbon soluble polymers prepared by copolymerizing (1) divinylbenzenes with linear alpha-olefins and (2) vinylsiloxanes with linear alpha-olefins. In one aspect the invention relates to the method of reducing friction loss of hydrocarbon streams flowing through conduits by adding such non-crystalline, hydrocarbon soluble copolymers to such hydrocarbon streams.